There is an approximately 1 in 40 likelihood of a new donor matching with an unrelated donor, with some matching more than once. In the future, a donors match likelihood is likely to increase due to the recent studies showing the efficacy of PBSC transplants for patients suffering from MS and ALS.
Stem cell donors are heroes and they deserve to be compensated. With Pareto, donors receive $10,000 for their stem cell donation. This is a lot of money, but you are providing a potentially life-saving cure.